1. Field of the Invention
This invention relates to a process for the continuous production of granular detergent and/or cleaning compositions, dust-free and non-greasy granules preferably having an apparent density of 600 to 1000 g/l being obtained through suitably selected process conditions.
2. Discussion of Related Art
Numerous proposals for the batch production or continuous production of compacted granules are known from the prior art. Either high-speed, rapidly rotating mixer/granulators are used or two mixer/granulators are arranged in tandem, the first mixer/granulator being a high-speed, rapidly rotating mixer/granulator and the second mixer/granulator being a low-speed, slowly rotating mixer/granulator. Thus, granulation processes in a high-speed, rapidly rotating mixer/granulator are disclosed, for example, in European patent applications 351 937 and 339 996.
Process in which a high-speed, rapidly rotating mixer/granulator and a low-speed, slowly rotating mixer/ granulator are arranged in tandem are described, for example, in European patent application 420 317 and in European patent application 390 251. According to EP 420 317, anionic surfactants in their acid form are first neutralized in the high-speed mixer/granulator and are then converted into granules with other constituents. These granules are plastic and are deformed in a low-speed mixer/granulator, resulting in compaction of the granules. The process is completed by a drying or cooling step. EP 390 251 describes a two-stage granulation process in which 0.1 to 40% by weight of the solid starting material is added after the first granulation stage (high-speed mixer/granulator) and optionally during the second granulation stage (low-speed mixer/granulator).
One feature common to these known processes is that, although the granules obtained by them have an apparent density of around 600 to 900 g/l, they do tend to cake and to become tacky and greasy unless the processes are carried out in the substantial absence of water and/or in the substantial absence of nonionic surfactants and/or in a certain temperature range. In addition, the required apparent density can only be established to a certain extent.
Accordingly, the problem addressed by the present invention was to provide a process for the continuous production of dust-free and non-greasy, non-caking and non-tacky granular detergents and/or cleaning compositions containing anionic surfactants and nonionic surfactants in substantial quantities. In addition, the process according to the invention would enable both the required apparent density of the granules to be established and granules with a relatively small percentage of coarse particles to be produced.